cross-fertilization

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Fertilization by the union of gametes from different individuals, sometimes of different varieties or species.
• noun Mutual exchange, as between dissimilar concepts, cultures, or classifications, that enhances understanding or produces something beneficial.

from The Century Dictionary.

• noun In botany, the fertilization of the ovules of one flower by the pollen of another, on the same plant or on another plant of the same species.
• noun In general, the sexual union of two germ-cells from two parent organisms, as contrasted with self-fertilization in plants and in some hermaphrodite animals.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Fertilization by the union of gametes of different plants (sometimes of different species).
• noun by extension The mutual exchange of ideas or concepts from different fields for mutual benefit.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun interchange between different cultures or different ways of thinking that is mutually productive and beneficial
• noun fertilization by the union of male and female gametes from different individual of the same species